From patchwork Sat Sep 5 10:27:21 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andreas Gruenbacher X-Patchwork-Id: 7128431 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 7C3A0BEEC1 for ; Sat, 5 Sep 2015 10:37:34 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 87E9420787 for ; Sat, 5 Sep 2015 10:37:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CA25F20821 for ; Sat, 5 Sep 2015 10:37:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753208AbbIEK3n (ORCPT ); Sat, 5 Sep 2015 06:29:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58433 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752048AbbIEK21 (ORCPT ); Sat, 5 Sep 2015 06:28:27 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (Postfix) with ESMTPS id C317C461D2; Sat, 5 Sep 2015 10:28:27 +0000 (UTC) Received: from nuc.home.com (vpn1-7-178.ams2.redhat.com [10.36.7.178]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t85ARbEJ023920; Sat, 5 Sep 2015 06:28:26 -0400 From: Andreas Gruenbacher To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-api@vger.kernel.org, linux-cifs@vger.kernel.org, linux-security-module@vger.kernel.org Cc: Andreas Gruenbacher Subject: [RFC v7 26/41] richacl: Apply the file masks to a richacl Date: Sat, 5 Sep 2015 12:27:21 +0200 Message-Id: <1441448856-13478-27-git-send-email-agruenba@redhat.com> In-Reply-To: <1441448856-13478-1-git-send-email-agruenba@redhat.com> References: <1441448856-13478-1-git-send-email-agruenba@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, SUSPICIOUS_RECIPS, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Put all the pieces of the acl transformation puzzle together for computing a richacl which has the file masks "applied" so that the standard nfsv4 access check algorithm can be used on the richacl. Signed-off-by: Andreas Gruenbacher --- fs/richacl_compat.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/richacl.h | 3 ++ 2 files changed, 113 insertions(+) diff --git a/fs/richacl_compat.c b/fs/richacl_compat.c index 412844c..9681efe 100644 --- a/fs/richacl_compat.c +++ b/fs/richacl_compat.c @@ -730,3 +730,113 @@ richacl_isolate_group_class(struct richacl_alloc *alloc) } return 0; } + +/** + * __richacl_apply_masks - apply the file masks to all aces + * @alloc: acl and number of allocated entries + * + * Apply the owner mask to owner@ aces, the other mask to + * everyone@ aces, and the group mask to all other aces. + * + * The previous transformations have brought the acl into a + * form in which applying the masks will not lead to the + * accidental loss of permissions anymore. + */ +static int +__richacl_apply_masks(struct richacl_alloc *alloc, kuid_t owner) +{ + struct richace *ace; + + richacl_for_each_entry(ace, alloc->acl) { + unsigned int mask; + + if (richace_is_inherit_only(ace) || !richace_is_allow(ace)) + continue; + if (richace_is_owner(ace) || + (richace_is_unix_user(ace) && uid_eq(owner, ace->e_id.uid))) + mask = alloc->acl->a_owner_mask; + else if (richace_is_everyone(ace)) + mask = alloc->acl->a_other_mask; + else + mask = alloc->acl->a_group_mask; + if (richace_change_mask(alloc, &ace, ace->e_mask & mask)) + return -1; + } + return 0; +} + +/** + * richacl_apply_masks - apply the masks to the acl + * + * Transform @acl so that the standard NFSv4 permission check algorithm (which + * is not aware of file masks) will compute the same access decisions as the + * richacl permission check algorithm (which looks at the acl and the file + * masks). + * + * This algorithm is split into several steps: + * + * - Move everyone@ aces to the end of the acl. This simplifies the other + * transformations, and allows the everyone@ allow ace at the end of the + * acl to eventually allow permissions to the other class only. + * + * - Propagate everyone@ permissions up the acl. This transformation makes + * sure that the owner and group class aces won't lose any permissions when + * we apply the other mask to the everyone@ allow ace at the end of the acl. + * + * - Apply the file masks to all aces. + * + * - Make sure the owner is granted the owner mask permissions. + * + * - Make sure everyone is granted the other mask permissions. + * + * - Make sure that the owner is not granted any permissions beyond the owner + * mask from group class aces or from everyone@. + * + * - Make sure that the group class is not granted any permissions from + * everyone@. + * + * The algorithm is exact except for richacls which cannot be represented as an + * acl alone: for example, given this acl: + * + * group@:rw::allow + * + * when file masks corresponding to mode 0600 are applied, the owner would only + * get rw access if he is a member of the owning group. This algorithm would + * produce an empty acl in this case. We fix this case by modifying + * richacl_permission() so that the group mask is always applied to group class + * aces. With this fix, the owner would not have any access (beyond the + * implicit permissions always granted to owners). + * + * NOTE: Depending on the acl and file masks, this algorithm can increase the + * number of aces by almost a factor of three in the worst case. This may make + * the acl too large for some purposes. + */ +int +richacl_apply_masks(struct richacl **acl, kuid_t owner) +{ + if ((*acl)->a_flags & RICHACL_MASKED) { + struct richacl_alloc alloc = { + .acl = richacl_clone(*acl, GFP_KERNEL), + .count = (*acl)->a_count, + }; + if (!alloc.acl) + return -ENOMEM; + + if (richacl_move_everyone_aces_down(&alloc) || + richacl_propagate_everyone(&alloc) || + __richacl_apply_masks(&alloc, owner) || + richacl_set_owner_permissions(&alloc) || + richacl_set_other_permissions(&alloc) || + richacl_isolate_owner_class(&alloc) || + richacl_isolate_group_class(&alloc)) { + richacl_put(alloc.acl); + return -ENOMEM; + } + + alloc.acl->a_flags &= ~(RICHACL_WRITE_THROUGH | RICHACL_MASKED); + richacl_put(*acl); + *acl = alloc.acl; + } + return 0; +} +EXPORT_SYMBOL_GPL(richacl_apply_masks); diff --git a/include/linux/richacl.h b/include/linux/richacl.h index 832b06c..a945f3c 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -332,4 +332,7 @@ extern struct richacl *richacl_inherit(const struct richacl *, int); extern int richacl_permission(struct inode *, const struct richacl *, int); extern struct richacl *richacl_create(struct inode *, struct inode *); +/* richacl_compat.c */ +extern int richacl_apply_masks(struct richacl **, kuid_t); + #endif /* __RICHACL_H */